With lawmakers eager to hit the campaign trail, Senate Democratic leaders struggled this evening to strike a deal with Republicans to expedite the passage of a stopgap spending bill to fund the government through March.

After agreeing to hold a vote on Sen. Rand Paul's (R-Ky.) proposal to cut off certain foreign aid, Senate Majority Leader Harry Reid (D-Nev.) encountered an objection from Sen. John McCain (R-Ariz.), who said the amendment needed more debate time than the hour that was being offered. McCain also sought to offer his own foreign aid proposal, saying he feared for the "safety and security" of U.S. diplomatic personnel if Paul's amendment were adopted.

Paul had threatened to keep the Senate in session through Sunday unless he got a vote on his amendment to cut off foreign aid to Egypt, Libya and Pakistan.

Earlier today, Reid told reporters, "I've had conversations with Rand Paul last night and today. I have had conversations with the Republican leader, Republican Senators and my own Senators. And we're working our way through that now. We don't have a direct path, but we're working on it."

The House passed the continuing resolution last week, and if it is altered in the Senate, the measure would have to go back to the House for its approval.

The back-and-forth threatened to keep the Senate in session until Sunday, when the final passage vote on the CR would occur if all 100 Senators did not give unanimous consent to hold it earlier. However, it appeared by this evening that - despite the partisan sniping - a time agreement was within reach.

But at the end of this evening's session no agreement was reached.

Reid had told reporters today that he would give Paul a vote but that GOP leaders also had input in the decision.

"If it's up to me and my Democrats, the answer is yes, but it's up to the Republicans," Reid said when asked whether he would allow Paul's amendment.

Though McCain later emerged as a roadblock to the deal to vote on the Paul amendment, a GOP aide had disputed Reid's claim that Republicans were holding up any decision on the issue.

"The Majority Leader has blocked this proposal for months. He's bluffing," the aide said.

But GOP foreign policy hawks such as McCain and Sen. Lindsey Graham have not exactly kept their disdain for the measure a secret.

"When they write the history of these times, I am not going to be part of a Congress that cut ties with the world at a time when it mattered to be involved," the South Carolina Republican said Wednesday.

Paul initially sought to cut off aid to just Pakistan over that government's imprisonment of Dr. Shakil Afridi. Afridi aided in the covert military operation that resulted in the killing of Osama bin Laden.

But he subsequently expanded his amendment to cover Egypt and Libya after recent attacks on U.S. government facilities in those countries resulted in the deaths of four Americans, including the U.S. ambassador to Libya, Christopher Stevens.

"American taxpayer dollars should not go to Libya until the murderers are delivered to justice," Paul wrote in an op-ed that ran today in the Washington Times. "Nor should they go to Egypt until the Egyptians prove that they are willing and able to protect our embassy. Finally, not one more penny of American taxpayer dollars should go to Pakistan until the doctor who helped us get bin Laden is freed."

Paul has pledged to use any procedural maneuvers at his disposal to get a vote on his amendment.

"The CR is not due until Sept. 30, but because my colleagues in the Senate seem to value their campaigning time, the Senate is trying to vote on the CR this week and leave until the election," Paul said. "I regretfully apologize to all of my colleagues, as I am told my filibuster will put a kink in their campaign plans and flights home this week."

The dustup over the Paul amendment could also delay any other business the Senate could conduct between now and when the chamber recesses.

One measure that is in the mix is legislation sponsored by Sen. Jon Tester (D-Mont.) that would ease restrictions on hunters and sportsmen, including allowing permits for people carrying bows and crossbows to traverse national parks when such a route provides the most direct access to hunting grounds.

Another bill that could come up is the tax extenders package approved by the Senate Finance Committee last month.

Reid and McCain lamented the 112th Congress' distinction as the least productive in modern history, with both blaming the other party for the gridlock.

McCain complained that Democrats have offered Senators precious little debate time over the course of the Congress, leading to GOP resistance.

But Reid told the Senate, "His agitation should not be directed toward me. ... They're the ones holding up hundreds of bills."